The present invention relates to a remote control signal processing device, more particularly to a remote control processing device for a remote control system comprising a remote control apparatus and a remotely controlled machine such as TV, VTR or audio equipment.
FIG. 1 shows conceptually two sets of remote control system consisting of two remote control apparatus and two machines that are to be remotely controlled with these apparatus. These two sets are of different types in that the code and format of the remote control signal employed by one set do not overlap those of the signal used for the other set. In other words, machine A.sub.1 is remotely controlled with a remote control signal a supplied from a remote control apparatus A.sub.2, whereas machine B.sub.1 is remotely controlled with a remote control signal b supplied from a remote control apparatus B.sub.2. However, aparatus A.sub.2 is unable to remotely control the machine B.sub.1, and apparatus B.sub.2 is incapable of remotely controlling the machine A.sub.1. Therefore, in order to remotely control two machines A.sub.1 and B.sub.1 in two different types of remote control system, two remote control apparatus adapted for the respective machines have to be operated but this reduces the operating efficiency of the remote control systems.
In order to deal with this low operability problem, a stack-type remote control apparatus has been proposed that is used as a single unit to remotely control a plurality of machines. This stack-type remote control apparatus is shown in FIG. 2 in which it is identified by C. The code and format of each of the remote control signals a and b from two remote control apparatus A.sub.2 and B.sub.2 are preloaded in the memory unit of the stack-type remote control apparatus C in storage areas associated with operating keys in this apparatus. When a certain of these operating keys are depressed, preloaded code and format are selectively used to reconstruct the associated remote control signal which is supplied to the respective machines A.sub.1 and B.sub.1 for controlling them remotely.
FIG. 3 is a system block diagram of stack type remote control apparatus. In order to record remote control signals, a select switch 11 is set into a reception mode and a remote control apparatus (not shown) is operated to send a remote control signal a while operating keys 12 are manipulated. The signal a is received by a reception unit 13.
The remote control signal received at the reception unit 13 is sent to a demodulating unit 14, where it is converted to signal data based on the code and format of that remote control signal and then delivered to a memory unit 15.
Manipulation of the operating keys 12 also produces associated address data from a key input unit 16 and the memory unit 15 is accessed in response to this address data so that the delivered signal data is written into this memory unit 15.
In order to perform remote control, the select switch 11 is set into a transmission mode and a certain of the operating keys 12 are manipulated, whereupon loaded signal data is read out of storage areas in the memory unit 15 that are associated with the depressed keys.
In a coding unit 17, a code and a format are set on the basis of the signal data read out from the memory unit 15 and a remote control signal is transmitted from a transmitting unit 18 in accordance with the so set code and format.
As will be understood from the above explanation, the major advantage of the stack-type remote control apparatus is that it is assembled into a single unit and that the remote-controlled devices can be operated by merely operating that one unit. However, the stack-type remote control apparatus has to store as many remote control signals as the remote control apparatuses of different types and this necessitates the use of a memory unit 15 with large storage capacity. Furthermore, the extra need to install a reception unit 13 for receiving several different remote control signals increases the size and cost of the stack-type remote control apparatus as compared with ordinary non-stack types.
Further, a conventional remote control apparatus having learning capability is shown diagrammatically in FIG. 4.
In this figure, 1 denotes a signal receiving unit that receives a remote control signal I to be learned that is transmitted from a different remote control apparatus; 2 denotes an operating key that is manipulated to read out of a memory unit 4 either the remote control signal programmed in an arithmetic processing unit 6 or the learned signal; and 3 denotes mode select switch for switching a signal reception mode to a signal transmission mode or vice versa.
Further referring to FIG. 4, the numeral 4 denotes the memory unit for storing signal elements, 5 denotes a control unit which, upon analyzing the signal received at the receiving unit 1 and comparing it with a reference signal, stores the elements of that received signal in the memory unit 4 and reads the stored signal elements from said memory unit 4 so as to reconstruct a signal, 6 denotes the arithmetic processing unit having the control unit 5, 7 denotes a display unit for displaying the sequence of operations to be executed by the remote control apparatus, and 8 denotes a signal transmitting unit from which the signal reconstructed in the control unit 5 is transmitted by a certain medium such as infrared radiation toward the machine to be controlled.
The remote control signal I to be learned may have the waveform shown in FIG. 5. The periods T.sub.1 -T.sub.4 have different durations of On and OFF times so as to provide pulses with different duty ratios.
As shown in FIG. 6, the memory unit 4 is composed of a parameter storage section 4.sub.1 and a signal element storage section 4.sub.2. The parameter storage section 4.sub.1 stores the elements of the remote control signal I having the waveform shown in FIG. 5, whereas the signal composition storage section 4.sub.2 stores the composition of the remote control signal I. In practice, the signal composition storage section 4.sub.2 stores the addresses of the individual signal elements stored in the parameter storage section 4.sub.1.
The remote control apparatus having the composition described above will be operated in the following manner.
When the mode select switch 3 is set into a signal reception mode, the arithmetic processing unit 6 becomes ready for signal reception. Then, the remote control signal I (e.g. an IR signal) to be learned that is sent from a different remote control apparatus is detected with the reception unit 1 and converted into an electric signal for supply to the control unit 5. This control unit 5 contains a timer, a counter and a program means and measures the elements, such as the number of pulses per unit time and the time interval between pulse bursts, of the remote control signal I detected in the reception unit 1. The measured signal elements (T.sub.1 -T.sub.4) are stored in the parameter storage section 4.sub.1 of the memory unit 4. The composition of the remote control signal I is stored in the signal composition storage section 4.sub.2 of the memory unit 4 in terms of the addresses at which the measured signal elements are stored in the parameter storage section 4.sub.1.
By repeating the above-described sequence of operations, erroneous reading of the remote control signal I to be learned is prevented in such a way that if the initially received and stored remote control signal I coincides with the remote control signal I received at the second time, reception date (signal elements) for the remote control signal I is stored in fixed areas of the memory unit 4 in association with the layout of operating keys 2.
The mode select switch 3 is then set into a signal transmission mode. If, in this mode, a certain of the operating keys 2 in association of which "learning" has been completed is depressed, the signal elements associated with said depressed key are read out of the memory unit 4 (consisting of the parameter storage section 4.sub.1 and the signal composition storage section 4.sub.2) under the control of the control unit 5 while, at the same time, the signal that has been learned in the manner described above is reconstructed for supply to the transmission unit 8. In the transmission unit 8, the signal reconstructed by the control unit 5 is converted to some suitable carrier signal such as IR radiation, which is sent out as an outgoing signal for controlling the operation of the machine to be controlled. The sequence of these steps is displayed on the display unit 7 under the control of the control unit 5.
Having the composition described above, the conventional remote control apparatus having the "learning" capability requires a memory unit with sufficient storage capacity to store the composition and parameters of a received signal. This remote control apparatus is not only expensive but also undesirable from a practical viewpoint since the memory unit requires a large installation area.